Hypergraphia is a manifestation of mental illness, in which someone has a huge amount to say, and writes it all over their car, or house, or cardboard signs that they hold up.
Just about every inch of this truck is covered in writing, mostly about criminal things the government has done. If you click on the picture, it will enlarge, and you can read about these crimes.
I believe this truck belongs to a woman often seen at a busy intersection in Redwood City, waving signs, sometimes inside a large garment covered with writing. I remember reading about her covering her house with writing, and how it upset the neighbors. I hope she gets help, or finds happiness getting her message out.